A W-3 Form is a transmittal form which is sent to the Social Security Administration (SSA) showing total earnings, Social Security wages, Medicare wages and withholding for all employees for the previous year To prepare a W-3 form, you must add up wages for all employees in each category and use them to complete the W-3 form.
The W-3 form is required to be sent to the SSA no later than the end of February, along with a Copy A of the W-2 W-2 forms for each employee. The totals for each item on the W-3 must equal the totals for all of these items on all employee W-2 forms. The W-3 also includes total state wages and withholding for all employees.
Read more about filing Form W-3 and Form 1096.